According to Danny Knobler
BALTIMORE -- Placido Polanco missed a fourth straight game tonight because of his stiff back, but he said it's much improved. He took BP in the cage, and doesn't sound nearly as worried (the doctor told him it's muscular). Jim Leyland is going to be very cautious. He knows he has to stay away from long-term injuries.
Placido is a major part of this lineup and I would love to see him contributing once again pretty soon. Tigers utility infielder Omar Infante has been getting more PT with Polanco being out, and has gone a combined 3 of 10 with 2 RBI over the last 3 games.